INTRODUCTION: The prevalence of pulmonary hypertension in end-stage renal disease (ESRD) patients receiving hemodialysis (HD) has been documented to be 29%-52% [Ref 1] by echocardiography. With the rising burden of patients with ESRD, pulmonary hypertension in this cohort will be a significant problem for the health-care providers. Different mechanisms have been attributed to the pathogenesis of pulmonary hypertension in patients with ESRD on HD. Alterations in endothelium-dependent vasodilators have been proposed as one of the mechanisms causing pulmonary hypertension [Ref 2]. We present a case of pulmonary hypertension in ESRD on HD that had significant clinical and hemodynamic improvement with dual endothelin-receptor antagonist, bosentan.
CASE PRESENTATION: A 32-year-old African-American female was referred to our pulmonary hypertension clinic for WHO functional class III dyspnea and systolic pulmonary artery pressure of 110 mmHg on echocardiogram. At presentation she had dyspnea on exertion after walking one block that was limiting her activities of daily living. Her past medical history was significant for systemic hypertension, ESRD on HD for 15 years, status post failed renal transplant twice, and multiple arteriovenous fistulae. On examination she had elevated JVP, loud P2, right ventricular heave, palpable liver 6 cms below the right costal margin, and dependent edema up to the mid-shins. Her initial work-up for pulmonary hypertension included V/Q scan, liver function tests and autoimmune panel. She underwent a right heart catheterization, and was started on bosentan. She had marked improvement in activities of daily living on bosentan therapy to the point where she was able to go back to work. After a year and a half of treatment her WHO functional class improved from III to I. We repeated the right heart catheterization, which showed that the RA pressure had declined from 21 to 3 mmHg, mean PA pressure from 52 to 24 mmHg, pulmonary vascular resistance from 9.1 to 3.3 Wood units, and pulmonary capillary wedge pressure from 20 to 7 mmHg. The cardiac index improved from 2.4 to 3.4 L/min/m<sup>2</sup>. There was no significant change in her systemic blood pressure with bosentan therapy.
DISCUSSIONS: Various contributing factors are involved in the pathogenesis of pulmonary hypertension in patients with ESRD on HD. Volume status, diastolic dysfunction, pulmonary vascular disease, and high cardiac output from a left-to-right shunt across the arteriovenous fistula, can all contribute to pulmonary hypertension either singly or in combination. Delineating these 4 etiologies can be difficult without invasive hemodynamics. Our patient had evidence of diastolic dysfunction and fluid overload at initial catheterization as suggested by the elevated wedge pressure. However, the fall in pulmonary vascular resistance by 64% with marked improvment in cardiac index is strongly suggestive of pulmonary vascular disease as the primary underlying etiology for her pulmonary hypertension.
CONCLUSION: The reversal of pulmonary hypertension with dual endothelin-receptor antagonist in our patient supports the hypothesis that in patients with ESRD on HD, there is an alteration in endothelium-mediated vasodilators causing vasoconstriction and pulmonary hypertension. The pharmacokinetics and safety of bosentan in ESRD has already been demonstrated. This is the first reported case of improvement of pulmonary hypertension associated with ESRD on bosentan therapy.
DISCLOSURE: Tabarak Qureshi, None.